Which is the best place to train? I need to train a lot going to Via Infinito......but I need a good place to train.

I personally liked training in the area b4 the last boss, tons of exp there, if ya can live long enough :P

The idea that you need to train a lot before going into the Via Infinito is myth. The Via Infinito should be your training grounds. The monsters for like the first 20 floors are all really sucky. The monsters for the second 20 floors are semi-sucky. The ones for the third 20 floors are kinda tough, but by then you should have gotten plenty of EXP from the first 40 anyway that you should be okay. Fourth set of 20, rather tough, but by then, your levels should be pretty good and by the final 20, you'll be facing the tough enemies, but you'll also be gaining lots of EXP. And if it starts getting kinda tough, you can stop and train in one area for as long as you like.

I will tell you something, but it's not joking
some one in www.gamefaqs.com said that:

" Do you know the travel agency in macalani woods? There will be some way that you can't go through, it's like a "wall" that will make you return to travel agency each time you want to get pass it, and you will evenetually run into a fiend.

Nah, that's the good place
you can level up your characters by these steps:
1. Buy 2 rubber band
2. Use that two rubberbands to stick the left and X button
3. Before doing the second step above, just try killing some fiends there by just hold on X button until you are sure there is some problem
4. Get sleep and turn off your TV
5. In your next day, it should be a lot of EXP! and gils"

I haven't try it,but it makes senses:)

The monsters for like the first 20 floors are all really sucky

that is bull i came one the second floor and i got killed by one of those rede dragon dudes from mt gagazet. he killed rikku in one hit with damage : 4112 and then he killed paine and yuna so i had no chance

you mean Elder Drake, zhao yun?
the red dragon that strike forward and back continously?
how bout berserker's evad and counter ability? it works nice for me:)

Or how about avoiding the Elder Drake. Yeah, you had no chance because you weren't supposed to fight it. Stand in the area right before it, wait for it jump out then go back into its little hole and then run by. Later on, there'll be others as well and Mega Tonberries to boot, but they're all avoidable if you know what you're doing. Or try Berserker's Evade and Counter, like j3 said.

i didnt know that at the time

Can;t really say much about elder drake,because sooner or later you will encounter it in random battle, even worse, you will encounter it partnering with another fiend(it's powerful too). I suggest you are ready for it, I wonder if we can flee from the random encounter with elder drake(never try it:()

Yeah, you can escape from it. You can escape from all of the random battles in the Via Infinito. Only the boss battles and the set encounters with Mega Tonberries and Elder Drakes can't be escaped from (although those last two can always be avoided.)

Of course, though, by the time you get to those levels, you should probably have enough EXP / power to take on those monsters, unless you've been escaping on the earlier levels. Or just use 777 Random Reels Pause trick and finish them off pretty easy no matter how sucky you are. (in most cases)